Radio control devices such as model airplanes, model boats, model cars or the like, have developed a considerable following in the marketplace. A typical model airplane, for example, includes a plurality of servo control devices such as throttle, rudder, aileron and elevator. While such systems could be directly controlled by a hardwired hand-held control device, this would severely limit the freedom of flying. Preferably, the airplane is controlled by a radio control system.
Such a radio control system includes a hand-held control box. The box houses plural input devices such as joysticks and trim tabs. The position of these input devices is varied to control operation of the airplane. The control box further houses an encoder which encodes user input commands from the input device into a digital signal conveyed to a transmitter. The transmitter transmits a through the air signal based on the digital signal. The model airplane includes a receiver receiving the transmitted signal and using the received signal to control the servo devices.
Digital proportional radio control systems have become popular to control the previously described devices such as model airplanes, boats and cars. Commercially available DPRC systems range from as few as two channels to as many as eight channels. Each channel is associated with controlling a servo system in the controlled device. For example, controlling an engine's throttle requires a separate channel.
A typical control box includes four channels for controlling throttle, rudder, ailerons and elevator. The associated model airplane would include a servo motor and system for each of these controlled elements.
As a model airplane flyer becomes more adept, there may be a desire to enhance the features of the airplane as by adding additional servo systems or to provide more sophisticated control. The typical receiver is capable of interfacing with such additional servo systems. However, the control box is limited due to the number of user input devices included thereon. Thus, to upgrade a model airplane has heretofore required the purchase of an entire new control box including a greater number of input devices and channels, as well as the basic encoder and transmitter. Doing so can be prohibitively expensive.
The present invention is directed to solving one or more of the problems discussed above in a novel and simple manner.